Conventionally, there has been known a bearing unit including a bearing and a shaft rotatably supported on a bearing surface of the bearing (see patent document 1, for example).
FIG. 14 is a view for explaining a conventional bearing unit 910. The conventional bearing unit 910 includes, as shown in FIG. 14, a bearing 930 having a bearing surface 932, a bearing 960 having a bearing surface 962, and a shaft 920 rotatably supported on the bearing surface 932 of the bearing 930 and the bearing surface 962 of the bearing 960.
The bearing 930 includes, as the bearing surface 932, a radial bearing surface 934 and a thrust bearing surface 936. The shaft 920 has a thrust plate 922 disposed at a position sandwiched between the thrust bearing surface 936 of the bearing 930 and the bearing surface 962 of the bearing 960, and is rotatably supported on the radial bearing surface 934 and the thrust bearing surface 936 of the bearing 930 and the thrust bearing surface 962 of the bearing 960. A lubricant (not shown in the drawing) is filled in a gap defined between the bearing surface 932 of the bearing 930 and the shaft 920 and in a gap defined between the bearing surface 962 of the bearing 960 and the shaft 920.
According to the conventional bearing unit 910 having such a constitution, due the presence of the lubricant in the gap defined between the bearing surface 932 of the bearing 930 and the shaft 920 and in the gap defined between the bearing surface 962 of the bearing 960 and the shaft 920, the bearing performance of the bearing unit can be enhanced.    [Patent document 1] JP-A-2004-176816